The present invention relates to an improved punch which is used in conjunction with a punch driver to punch holes in a work piece, such as for example, sheet metal, aluminum, fiberglass and plastic.
Generally, when a hole is to be punched in a work piece, a small pilot hole is first drilled in the work piece. A punch assembly is then used to create a hole of the desired dimensions in the work piece. A prior art punch assembly 10 is shown in FIG. 1. The punch assembly 10 includes a die 12, a punch 14, and a draw stud 16. A first end 18 of a draw stud 16 is threaded into a ram 20 of a hydraulic punch driver 21. The operator locates the punch assembly 10 in the pilot hole 24 by using “alignment marks”. A second end 22 of the draw stud 16 is inserted through the die 12 and then through the drilled pilot hole 24 in the work piece 26, the draw stud 16 having a circumference that is less than the circumference of the drilled hole 24. The punch 14 is threaded onto the second end 22 of the draw stud 16 on the opposite side of the work piece 26 from the die 12 and the driver 21. An operator actuates a hydraulic punch driver 21. When the hydraulic punch driver 21 is actuated, hydraulic fluid forces the ram 20 to pull the draw stud 18. The draw stud 18, in turn, pulls the punch 14 through the work piece 26 into the die 12 such that the desired hole is punched in the work piece 26.
Punch assemblies used in the prior art suffer from a number of disadvantages. One such disadvantage is that the prior art punch assemblies do not provide means for locating the punch assembly in the pilot hole as the punch and the die are drawn together by the draw stud to make a hole in the workpiece. The alignment marks currently used to align the punch assembly with the pilot hole can be difficult to see by the operator and may allow for error such that the hole to be created may not be properly positioned.
Another disadvantage of prior art punch assemblies is that a significant amount of material is used to manufacture the punch which adds to the expense of the punch assembly.
Yet another disadvantage of the prior art punch assemblies is that the process for forming the punch can be very costly.
An even further disadvantage of the prior art punch assemblies is that the punch is costly to replace as it becomes worn after use.
Thus, it is desirable to have a punch assembly which incorporates the advantages of the prior art punches, but which overcomes the disadvantages of the prior art punch assemblies, such as those identified above. The invention, as described herein, provides such a punch assembly. Other features and advantages of the punch assembly of the present invention will become apparent upon a reading of the attached specification in combination with a study of the drawings.